Effect of the Electric Field on Ordering of Copper Phthalocyanine Films at the Molecular and Nano-scale

Abstract

Thin films of copper phthalocyanine (CuPc) have been prepared by vacuum thermal evaporation in the absence and in the presence of an applied electric field during film growth. It was found that both the film structure and its electrical properties were noticeably modified by the external field. Namely, molecular stacks become more ordered and conductivity of the films deposited under an external field was substantially increased as compared to the reference film. We discuss that although the CuPc molecules have small dipole moment in the ground state, nevertheless the induced dipole moment by the applied electric field can essentially promote orientation of molecular stacks in the film.